Ion engine could one day power 39-day trips to Mars

[n2doc]

Updated 17:50 23 July 2009 by Lisa Grossman

There's a growing chorus of calls to send astronauts to Mars rather than the moon, but critics point out that such trips would be long and gruelling, taking about six months to reach the Red Planet. But now, researchers are testing a powerful new ion engine that could one day shorten the journey to just 39 days.

Traditional rockets burn chemical fuel to produce thrust. Most of that fuel is used up in the initial push off the Earth's surface, so the rockets tend to coast most of the time they're in space.

Ion engines, on the other hand, accelerate electrically charged atoms, or ions, through an electric field, thereby pushing the spacecraft in the opposite direction. They provide much less thrust at a given moment than do chemical rockets, which means they can't break free of the Earth's gravity on their own.

But a new engine, called VASIMR (Variable Specific Impulse Magnetoplasma Rocket), will have much more "oomph" than previous ones. That's because it uses a radio frequency generator, similar to transmitters used to broadcast radio shows, to heat the charged particles, or plasma.

more:
http://www.newscientist.com/article/dn17476-ion-engine-could-one-day-power-39day-trips-to-mars.html

[Orrex]

1. Very cool. I'll have to keep an ion this story.

Hardy har har.

[eqfan592]

14. lol, nice :) (nt)

[Tesha]

15. You should be charged for a joke like that!

Next time, try to include at least a particle of humor!








;)

Tesha

[Peace Patriot]

2. I want one in my car! nt

[ret5hd]

4. 0-60 in 4.5 days.

Try merging on the freeway with that!

[Orrex]

10. That was the performance rating of the 85 Escort, by the way

Longer, if it was uphill.

[rug]

3. That's how long it took Columbus to sail the Atlantic.

[n2doc]

5. This is, of course, an "impulse" engine....

Engines ahead full, Scotty....

[GeorgeGist]

6. WTF is the rush?

Do martians have smaller egoes?

[pokerfan]

7. I'm holding out for the Infinite Improbability Drive

Though Warp Factor 2 would get us there in less than ten minutes.

[GreenPartyVoter]

9. You really shouldn't use Warp drive inside of solar systems, though.

[jobendorfer]

12. There's always the "bloater drive"

postulated by Harry Harrison in _Bill, the Galactic Hero_.
The ship is stretched to light years in length in the intended direction, then reshrunk from the stern forward to its normal length.
Of course, this is the writer who also postulated a jump drive powered by irradiated cheddar cheese, so please understand that he's as much a humorist as a science fiction writer.

On a serious note, though, a propulsion system that could accelerate a ship with even a tiny fraction of 1g would open up huge new possibilities, both for human and robot probe exploration. Journeys that would take years with conventional rockets could be done in months.

J.

[Johonny]

8. probably not

but ion engines are here to stay.

[Phoonzang]

11. Can we haz plz?

That would take away much of the arguments against going to Mars. 40 days is nothing. We have the technology to explore Mars right now. Cancel a couple of aircraft carriers and fund the mission. I'm hopeful Bolden will be able to talk Obama into it.

[pokerfan]

13. Yeah

VASIMR will be nice but we can go with chemical rockets via either http://en.wikipedia.org/wiki/Mars_Direct">Mars Direct or the latest http://en.wikipedia.org/wiki/Design_reference_mission_3.0">DRM. Six months there, 18 months on the surface, six months back give or take. Long enough to do some real work, not just planting a flag. Spin the habitat against the spent last stage on the way out to generate some artificial gravity. Exposure to cosmic radiation would certainly be reduced by a shorter trip because even though Mars has little atmosphere and not much of a magnetic field, just being on the surface of a planet cuts cosmic radiation in half. Solar flares are the big danger but they are rare (or at least the severe ones are rare) and with flares you get about an hour's warning. Plenty of time to get into the shelter which could simply be water/food stores.

[Phoonzang]

16. The VASMIR will almost completely negate the radiation risk though

A little over a month of exposure vs. 6 months. Like you said, being on Mars will cut the risk substantially as well because of atmospheric protection. I think we need to further develop VASMIR before we go past the moon. Maybe I'm just distrustful of chemical rockets... Maybe I just think it's time we start using alternate propulsion systems more robustly.

Anyway, it's up to the American people I guess. Do they have the will to begin the expansion into space or will they fall into the "we've got to make everything perfect here before we go out there" camp.

Edit: I did forget about the whole problem with having a nuclear reactor (to power the VASMIR) in space though. Might be some big political hoopla about that. Hopefully we (specifically DU-type liberals) can grow up and not connect nuclear power on a spacecraft to nuclear weapons in space.

[pokerfan]

17. I wouldn't go so far as to say completely negate

Eighteen months on the surface still equals nine months in deep space. No doubt any long term colony would be shielded with Martian regolith. Still, it's a small marginal risk, far less than other cancer risks such as smoking. I seriously doubt there would be any lack of volunteers for such a mission.

Another criticism regards the psychological demands of thirty months alone with only 3 to 5 other people. The claim is that people would go crazy on such a long voyage. Nonsense. Compare it to the early years of sea exploration where crews had to live cramped on a small boat possibly with a tyrant for a captain, horrible food, and no possible way of communicating with their loved ones for many months or years. Contrast that with the first Mars crew which would have all the comforts of home: TV (sent from earth), email, movies, good food, etc.

Anyway, it's up to the American people I guess. Do they have the will to begin the expansion into space or will they fall into the "we've got to make everything perfect here before we go out there" camp.

If we wait for that, then we will never go. Exploring Mars doesn't absolve us from addressing problems here on earth but the costs should be put into perspective. A single Mars Direct mission would involve just two launches, each somewhat larger than a current shuttle launch. In the meantime we've launched the space shuttle 126 times (while killing 14 astronauts) without ever leaving low earth orbit.

...not connect nuclear power on a spacecraft to nuclear weapons in space.

It's been done before. The Viking landers were nuclear powered as well as every probe to the outer planets where solar simply isn't feasible due to the diffuse insolation at those distances from the sun.

My point is that don't need to wait for VASMIR before we go.

[Phoonzang]

19. I don't have any disagreements with what you are saying...we could

send a mission to Mars with current technology on a 6 month journey. But there's something about the Mars Direct architecture that bothers me. I'm only a space enthusiast and not a scientist so I don't know whether these concerns are valid or not...

The Direct mission requires fuel and supplies be sent to Mars before the astronauts themselves. Assuming the "supply ship" lands safely and can manufacture fuel (if that's the route they're going), what happens if the there's a problem crewed spaceship lands far off course from the supply ship. We're talking hundreds of miles here. It seems like they'd be pretty much screwed, right?

Wouldn't it be safer to take most of your fuel and supplies with you to Mars, using a more powerful propulsion system rather than rely on the two-stage solution?

[pokerfan]

21. Sure

But the http://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation">rocket equation starts biting you in the ass. The rocket equation shows the relationship between delta-vee (change in velocity) and the required mass ratio (of payload to propellant). Basically, if you need twice the delta-vee (a Mars return doesn't but for the sake of argument...) then you need four times the rocket. Now it doesn't take the same delta-vee to return from Mars as it did to get there (it's about 40% more so 1.4² = 2) and surprisingly, it's actually less delta vee to reach the surface of Mars than the Moon:

The Mars Direct plan involves sending a second ERV (Earth Return Vehicle) along with the astronauts. It's intended to serve as the return ship for the next crew twenty-five months later (the minimum energy transfer orbit window opens up every twenty-five months) but would also serve as a backup for the first crew:



Well, since we're talking about aerobraking, it would pretty hard to land out of rover distance of the first ERV and survive to put it grimly. It's like the Apollo capsules and the CEV that NASA's designing for the Orion. Come in too shallow and you skip off. Come in too steep and you're crushed by the gees and/or burn up.

But let's suppose anyway that they did somehow land too far from the first ERV and further suppose that their accompanying ERV also landed too far away (or both ERVs malfunction in such a way that they can't make a single working ERV out of both). Well then they would simply extend their mission and be rescued (or resupplied) in twenty-five months. Aldrin even goes so far as to say that the first explorers should simply http://www.physorg.com/news143972922.html">go to Mars to stay. For any geologist worth her salt, 18 months would be too short anyway.

Are there risks? Absolutely. And these risks will never be zero no matter what redundancy is designed into the system. I tend to be risk-adverse: There needs to be some kind of a reward to offset the risk. We've lost fourteen astronauts while doing nothing more than spinning around in LEO for the last forty years. Challenger's mission was launching a god-damned communications satellite for pity's sake! If we're going to risk human life in space then let's do it for something more than launching satellites!

So why Mars? Off the top of my head:

1. Better understand our environment by studying another world's. Compare and contrast. How are they similar? How do they differ?

2. Search for life. We know that Mars had a warm, wet past. Even the existence of extinct Martian life would have huge implications for the frequency of life in the galaxy. Are we alone or is life common throughout the cosmos?

3. Longer term, perhaps become a two world species http://www.newscientist.com/article/dn13748-stephen-hawking-calls-for-moon-and-mars-colonies.html">as Hawking suggests. It's a bit of an understatement to suggest that we shouldn't have a full-scale nuclear war or continue to mess up our home but there are disasters beyond our control e.g. getting smacked by a comet or asteroid as did Jupiter a couple of weeks ago. As has already happened to Earth countless times.

Are those things worth 0.25% of our GDP as Hawking suggests? I say it is.

[Phoonzang]

22. Hmm, well the Mars Direct plan has more redundancy than I thought at first...

I hope we can do it. I'm still in favor of VASMIR, but we need to do SOMETHING. Soon.

As for risks...I'm risk averse not so much that I'm worried about the astronauts (though I wouldn't want anything to happen to them). I'm worried about a disaster shutting down manned space flight for good, which I think another accident would. Of course losing a manned mission to Mars is on a different level than losing a shuttle.

I read about Aldrin's idea that we should send people to Mars "to stay." I'm not sure how that would play out. It would seem a bit like a death sentence. It's not as though we're sending them to another continent on Earth. It's not as if we're even sending them to Antarctica. It would be much easier if we didn't have to worry about bringing people back, but I just don't think we can ignore public opinion.Even though the vast majority of the public has no idea what's going on...

I agree with Hawking as well. We need to have a backup plan. Hell, I think it's worth 2 percent of our GDP (or more) to get us the out there. People don't realize that the advances caused by the exploration of space will be able to help us back here on Earth. Especially when it comes to sustainable energy and environmental control.

PS- That Rocket Equation almost made me have a seizure. I'm not the biggest fan of math... ;)

[joshcryer]

23. As Zubrin says, send smokers to Mars, but take away their cigarettes...

...and they have a lower chance of getting cancer.

[bananas]

18. There are two problems with nuclear power for spacecraft

and neither of them have anything to do with nuclear weapons.
1. Getting it up there: booster rockets have a tendency to explode.
2. Keeping it up there: interplanetary craft haven't always made it out of orbit, several of them have fallen back.

Nobody objects to small rtgs, the problem is with large rtgs or reactors. The objections to Cassini were because there were serious questions as to whether the rtgs would survive a launch explosion or a fly-by accident. Cassini could have been completely powered by solar cells, except they would have exceeded the weight limit by 1%. There were several ways around that:
a) Wait a few years for solar cell efficiency to improve.
b) Squeeze out 1% from the rest of the payload
c) Use a combination of smaller solar arrays with smaller rtgs or fuel cells.
d) Use a larger rocket
e) Split the mission into two probes
etc.

[Phoonzang]

20. It is true that getting the reactor into orbit is the dangerous part.

As for people connecting nuclear power in space with weaponization, that's not a concern I have at all. It's just something I've occasionally heard expressed around here over the years.

As for the danger of solid fuel rockets exploding on launch, we have several models with very good safety records (the Ariane V comes to mind). It depends on how much risk one is willing to take.

As for Cassini, it may have been able to have been powered by current solar technology, but I THINK for a VASMIR to reach the "40 days to Mars" potential it absolutely must be powered by a nuclear reactor (I don't think an rtg would do it).

[krispos42]

25. What about using solar panels to power the ion drive?

Mars is still fairly close to the Sun, and we have solar cells that have on the order of 40% conversion efficiency. We could even use a kind of solar light sail to direct sunlight onto the solar cells. The weight of a smaller solar array and a big mylar sail would be significantly less per kilowatt-hour than a larger solar array of the same power output.


The sail might even pick up some of the solar wind, providing extra thrust to Mars.



I envision an array with a triangular cross-section with the "base" of the triangle pointing towards the sun and generating power from it directly, and the two angled sides having large mylar "sails" bouncing and concentrating solar light on them.



I hope I'm making sense. :-)

[Posteritatis]

24. Something to both

A quick trip there would leave more time to do things on the surface (or in the general neighborhood), but there's also something to be said for getting some experience with long-term spaceflight.